Oxford is very comparable in cost for a domestic UK student to UCLA for an in-state Californian student. The UK fees are GBP9250 ($11800) vs $13700 for UCLA. The estimated cost of food and accommodation at Oxford is GBP7500-10000 ($9500-$12700) vs $15800 for UCLA residence halls per the COA (though in fact the cheapest UCLA triple is $12900 including meal plan). However, the international premium for Oxford (varies by course but GBP18000 = $23000 is typical) is generally somewhat less than the OOS premium for UCLA ($29000). Also worth noting that the exchange rate is currently the most favorable it has been in the last several decades - for most of that time you would add 15%-25% (or more) to the dollar figures above when converting from pounds.
The main differences are that most UK degrees are three years instead of four, and the accommodation is mostly single rooms not triples. On the other hand aid for low income families is better in California. When you also take into account that graduate salaries are much higher in the US than the UK, UCLA is probably more affordable for most Californians than Oxford is for most Brits. “”
But another difference is that all UK students at a UK university are eligible for loans for tuition fees, which don’t need to be repaid until the student is earning a certain amount, and if they never make that salary, they never have to repay.